Silencer



C. C. MOSS Aug 5, 1941.

SILENCER Filed May 3, 1939 TTORNEYS.

Patented Aug. 5, 1941 SILENCER Chester 0. Moss, Jackson, Mich, assignor to Walker Manufacturing Company of Wisconsin,

corporation of Wisconsin Application May 3, 1939, Serial No. 271,542

8 Claims.

The present invention relates generally to the manufacture of silencers for use in connection with automotive vehicles and the like, and is more particularly directed to improvements in or relating to the forming of certain of the metal parts which comprise such silencers.

It will be appreciated from a complete understanding of the present invention that the improvements thereof are applicable to a wide variety of uses. However, a preferred application of the invention is in connection with the formation of the primary exhaust tubes of automotive exhaust silencers, and, by way of illustration, but not of limitation, the invention is so illustrated herein.

For the purposes of the present description, it may be noted that such silencers may conventionally comprise a primary exhaust tube, one end whereof may be connected to the engine exhaust pipe and the other end whereof may be connected to the usual tail pipe. The primary exhaust tube is received within a cylindrical outer shell, and may be supported therein by one or more partitions, the outer peripheries whereof may be joined to the outer shell and the inner peripheries whereof may be joined to the primary exhaust passage. The partitions also serve, as will be understood, to divide the space between the primary exhaust tube and the outer shell into one or more silencing chambers.

The primary exhaust tube is conventionally provided with openings in the wall thereof, which afford communication between the interior of the passage and the interior of the outer shell, and in many instances it is desirable to so form these apertures that the marginal portions thereof extend radially outwardly from the wall of the tube. With this relation, and to facilitate the assembly of the muflier as a whole, it has become conventional to provide the primary exhaust tube with an annular embossment at each point therealong at which a baille or partition or other cooperating part is to be connected thereto, the diameter of the embossment being slightly in excess of the outside diameter of the just mentioned marginal portions of the passage openings. In its present embodiment the invention is directed particularly to an improved method of forming the just mentioned annular embossments, whereby they may be impressed into the stock while it is in planar form without at the same time causing distortion of the stock when it is rolled into tubular form.

With the above as well as other considerations in view, the principal objects of the present invention are to provide an improved method of embossing sheet metal or the like in the practice of which the embossing may be eifected while the stock is in planar form and which does not interfere with the rolling of the stock into tubular or other form; to provide such a method wherein the embossment is constituted by a series of spaced embossment elements, the parts of the stock between each such element presenting a minimized resistance to bending, whereby the embossed stock may be rolled into tubular or other form without distortion; to provide such a method wherein the part of the stock between each such primary embossment element is impressed to a lesser extent whereby the annular embossment is of substantially continuous, uniform diameter, but comprises sections of successively greater and lesser resistance to bending; to provide a resultant muffler construction embodying one or more improved embossed sheet metal members having the above characteristics; and to provide a generally improved vehicle exhaust silencer and method of making the same.

With the above as well as other objects in view, which appear in the following description and in the appended claims, preferred but illustrative embodiments of the invention are shown in the accompanying drawing, throughout the several views of which corresponding reference characters are used to designate corresponding parts, and in which:

Figure l is a view in longitudinal section of an embodiment of the invention;

Fig. 2 is an enlarged View in transverse vertical section, taken along the line 2--2 of Fig. 1;

Fig. 3 is an enlarged view in vertical transverse section taken along the line 3-3 of Fig. 1;

Fig. 4 is an enlarged view illustrative of an intermediate forming step;

Fig. 5 is an enlarged view in section, taken along the line 5-5 of Fig. 4;

Fig. 6 is a view in section, taken along the line 6:--E of Fig. 4; and,

Figs. 7 and 8 are fragmentary views of a modification of the invention.

The silencer which has been selected as illustrative of the many silencer constructions in connection with which the present invention may be practiced, comprises generally an outer cylindrical shell IE) and an intermediate or primary exhaust pipe [2. The ends of the outer shell I0 are closed by partitions l3 and M, the outer marginal edges whereof are flanged so as to adapt them for connection, as by welding at a plurality of points H, to the inner surface of the outer shell l0, and the central portions whereof are formed as nipples l6 and I8, respectively. It will be appreciated that the nipple I6 is adapted for connection to the usual exhaust pipe leading from the associated internal combustion engine and that the nipple I8 is correspondingly adapted for connection to the usual vehicle tail pipe. The primary exhaust tube l2 extends substantial- 1y throughout the length of the outer shell H}, the forward end thereof being slidably connected within the nipple IB by means of the adapter 20, and the rear end thereof being secured, as by welding at a plurality of points ll, within the enlarged portion of the nipple [8.

In order to divide the space between the pri mary exhaust tube l2 and the outer shell iii into a plurality of silencing chambers, and also to provide intermediate support for the primary exhaust tube, a battle or partition 24 is provided.

The bafile 24 is provided with an outer peripheral I flange 26, which is snugly but slidably received adjacent the inner surface of the outer shell l0, and is also provided with an inner flange 22, which is secured, as by welding at a plurality of points 29 to a tuning sleeve 30. sleeve 38 is supported in spaced relation to the primary exhaust tube [2 by means of members 32 and 34, respectively, the inner and outer marginal flanges whereof are secured, as by welding to the sleeve 30 and to the embossments designated as a whole as 36 and 33. The embossments 36 and 38 are formed integrally with and extend radially outwardly from the primary exhaust pipe 12. As is described in more detail below, the improvements of the present invention are directed primarily to the formation of the embossments 36 and 38.

In accordance with the invention disclosed and claimed in the Gunn Patent No. 1,906,447, dated February 2'7, 193%, and assigned to the assignee of the present invention, the primary exhaust pipe I2 is provided with a plurality of groups of tangentially formed openings 4'.) and 42, which afford communication between the interior of the pipe [2 and the outer shell Ill. It will be noted that the openings 40 and 42 extend to some extent radially outwardly from the surface of the tube l2. The openings 48 are located ahead of the partition 24 and thus control communication between the interior of the primary exhaust passage l2 and the chamber space designated as a whole as 44. The openings 42 are located rearwa-rdly of the partition 24, and control the floor gases between the interior of the passage I2 and the chambers 45 and 43, the chamber 48 being represented by the space between the sleeve 38 and the tube 12, and the chamber 48 being represented by the space between the sleeve 30 and the outer shell IS. A communication between the chambers 46 and 48 in turn is controlled through a series of tuning openings 58. The proportioning and number of the chambers 44. 46, and 43, form no part of the present invention, and it is believed that no further description of the general operation of the mufiler is needed.

The embossments 36 and 35, to the formation of which the present invention particularly relates, may be characterized as having a form which enables them to be introduced into the stock while the latter is in flat form and which further enables the stock to be rolled into tubu lar or other form without distortion. More particularly stated, the embossments 36 and 38 are so formed as to have circumferentially spaced alternately arranged portions of The tuning relatively greater and relatively lesser resistance to bending, so that during the forming of the stock into tubular form, the principal bending in the stock occurs in the relatively weaker sections. The embossments are further so formed as to blend into the portions of the stock which are spaced axially on either side of each embossment, so as to further avoid distortion in such axial portions.

The embossments 3S and 38 are illustrated as being identical in construction, and they are preferably formed in the same manner, so that the description of one will suiiice for both.

Referring particularly to Figs. 2, 3, 4, 5, and 6, the embossment designated as a whole as 36, comprises a series of circumferentially spaced embossment elements 52, having crown portions 52a, side portions 521), and angularly related end portions 520 and 52d. In accordance with the preferred practice of the present invention, as previously mentioned, the embossment elements 52 are formed in the metal of the tube l2, while the latter is in a planar or flat condition, and may be formed by a suitable die forming operation simultaneously with the formation of the louver openings such as 4?]. It will be understood that the bending or rolling of the fiat sheet, Figure 4, into final form may be efiected in accordance with the usual practice, in any suitable forming machine. It will further be appreciated that, during such bending or rolling, the principal bending of the fiat sheet occurs in the spaces between successive embcssment elements 52, which intermediate spaces, being undeformed, offer little or no additional resistance to the bending or rolling, and thus do not distort the sheet during the forming process. In the broader aspects of the invention, the rolling or forming process may bring the sheet of Figure 4 from its initially substantially flat form into a variety of shapes. In the specific embodiment herein disclosed, the tube 12 is of closed form, the lateral meeting edges of the initially flat sheet being joined together by a conventional seam [2. The crowns 52a, as viewed in the sectional view in Figs. 3 and 5, are arcuately formed so that, in the finished tube, these crowns conform substantially to the curvature of the associated flange portion 28 formed on the partition 24. The formation of the end portions 52b and 520 of each embossment element 52 is of particular advantage in the practice of the present invention, and it will be noted that these two end portions are in angular relation to each other, each extreme end portion 52d extending some distance axially of the tube from the center of each embossment element. This relationship tends to blend the embossments into the adjacent undeformed axial portions of the tube and thus further serves to prevent distortion during the forming operation.

In assembling the muffler structure as a whole, it will be appreciated that the partitions 32 and as, either before or after they are secured to the tuning sleeve 38, may be slid along the body of the tube l2. This movement of the partitions 32 and 34 is not interfered with by the radially outwardly projecting mufiler openings, because of the fact that the diameter of the central opening in each partition is greater than the diameter of the circle in which the outer marginal portions of the muffler openings fall. On the other hand, the diameter of each central partition opening corresponds substantially to the diameter of the circle in which the arcuate crowns 52a of the embossment elements 52 fall, so that each partition is relatively snugly slidable into place upon its associated embossment. In order to securely fix the partitions in place, it is preferred to form a series of spot welds 54 between each partition flange and the corresponding embossment and the provision of the spaced embossments in accordance with the present invention introduces a further advantage in connection with this welding operation, since the spaced embossments inherently facilitate the proper spacing of the weld points circumferentially of the tube.

It will be noticed that in the embodiment now being described, the trough-like spaces between the embossment element 52 of the embossment 36 afford limited communication between the tuning chamber 44 and the tuning chamber 45. The corresponding trough-like spaces in the embossment 38 afford communication between the tuning chambers 46 and 48. It is found in practice that the limited communication thus afforded can be compensated for in the relative proportioning of the tuning chambers and it further appears in practice that in certain instances this additional limited communication improves the operation of the silencer as a whole.

To adapt the improvements of the present invention to those applications in which it is desired to prevent the just-mentioned limited communication between the respective chambers, the modified arrangement of Figs. 7 and 8 has been provided. In Figs. '7 and 8, the primary embossment elements 52 are joined together by intermediate embossment elements Hi. which are narrower in width then the primary embossment elements 52', but the crowns whereof project radially outwardly to substantially the same extent as the crowns of the primary embossment elements 52. By virtue of their narrower width, measured axially of the tube I2, the intermediate embossment elements III are found to present a substantially lower resistance to bending than is presented by the primary embossment elements 52'. Accordingly, when the initially flat stock, having the embossment elements 52 and 10 formed therein, is rolled into tubular form, the primary bending action occurs in the region of the intermediate embossment elements 10. As in the previous instance, the crowns of the primary embossment elements are of arcuate form and a corresponding but less pronounced arc is introduced into the crowns of the intermediate embossments ill during the forming operation. Accordingly, when the stock is rolled into tubular form, the peripherally successive embossment elements 52' and 10 present a continuous and uninterrupted cylindrical surface. This arrangement, therefore, affords the same advantages as are afforded by the embodiment of Figs. 1 through 6, and at the same time eliminates the previously mentioned trough-like spaces between the respective embossment elements.

It will be understood that in the foregoing description and in the claims, the term tubular body as applied to the primary exhaust tube I2 is used in a generic sense as comprehending tubes of cross sections other than circular and that the terms embossment, embossment elements, and the like, are used in a generic sense as comprehending parts or elements which project radially from the surface of the tubular body. It will be recognized that in the present embodiment, the imperforate partitions or baffles 32 and 34 serve to both support the tube [2 relative to the tube 39 and to cooperate with the tube 30 in defining the silencing chamber 46, which functions are illustrative of functions which can be performed by a member seated upon an embossment incorporating the present invention. Accordingly, the term partition, which appears in certain of the claims, is used in a generic sense as comprehending, for example, a member which performs a supporting function, a flow controlling function or a chamber defining function, or which combines such functions, and which may be either perforate or imperforate.

Although only two specific embodiments of the invention have been described in detail, it will be appreciated that further modifications in the form, number, and arrangement of parts and in the specific methods of practicing the invention may be made without departing from the spirit and scope of the invention as defined in the subjoined claims.

What is claimed is:

1. In combination, a partially or entirely closed tubular body formed of sheet metal or the like, an embossment projecting from the surface thereof characterized as being constituted by a series of peripherally spaced entirely closed embossment elements each extending from the surface of the body and being separated by portions of the body so shaped as to have lower resistance to bending than said embossment elements, and a partition member having a seating part conforming in curvature to the curvature of said embossment and seated upon said elements.

2. In a partially or entirely closed tubular body formed of sheet metal or the like and having a series of perforations distributed along over the surface thereof, marginal portions whereof project from the surface of the body, an embossment formed on the body to form a seat for a cooperating part, said embossment being characterized as constituted by a series of peripherally spaced entirely closed embossment elements each whereof projects from said surface at least as far as said marginal portions project therefrom, said embossment elements being separated by portion of lower resistance to bending than said embossment elements, and each said embossment element having the surface thereof shaped to con form to the shape of the corresponding portion of said cooperating part.

3. In combination, a generally tubular body formed of sheet metal or the like, an embossment projecting from the surface thereof characterized as constituting a succession of peripherally spaced entirely closed embossment elements each extending from the surface of the body, the space between successive said elements being substantially undeformed from the adjacent surface of said body, and a partition member having a seating part conforming in curvature to said embossment and seated upon said elements.

4. In combination, a cylindrical body formed of sheet metal or the like, an embossment extending substantially around the periphery of and projecting radially from said body, said embossment characterized as being constituted by a series of peripherally spaced entirely closed embossment elements each extending from the surface of the body and being separated by portions of the body so shaped as to have lower resistance to bending than said embossment elements, and a partition member having a seating part conforming in curvature to said embossment and seated upon said elements.

5. In a partially or entirely closed tubular body formed of sheet metal or the like, an embossment projecting from the surface thereof to form a seat for cooperating part, the curvature of said cooperating part conforming generally to the curvature of said body, said embossment being characterized as being constituted by a series of peripherally spaced entirely closed embossment elements separated by portions of the body so shaped as to have lower resistance to bendin than said embossment elements, and each said embossment element having the surface thereof shaped to conform to the shape of the corresponding portion of said cooperating part.

6. In a cylindrical body formed of sheet metal or the like, an embossment extending substantially around the periphery of and projecting radially from said body, said embossment characterized as being constituted by a series of peripherally spaced entirely closed embossment elements each extending from the surface of the body and being separated by portions of the body so shaped as to have lower resistance to bending than said embossment elements, the crowns of said elements being arcuate and lying in a circle substantially concentric with said cylindrical body.

7. In a cylindrical body formed of sheet metal or the like, an embossment extending substantially around the periphery of and projecting radially from said body, said embossment characterized as being constituted by a series of peripherally spaced entirely closed embossment elements each extending from the surface of the body and being separated by portions of the body so shaped as to have lower resistance to bending than said embossment elements, the crowns of said elements being arcuate and lying in a circle substantially concentric with said cylindrical body, and the end portions of each said element being formed to blend gradually into the adjacent surface of said body.

8. In combination, a generally tubular body formed of sheet metal or the like, an embossment projecting from the surface thereof characterized as constituting a succession of peripherally spaced entirely closed embossment elements each extending from the surface of the body, the space between successive said elements being occupied by entirely closed rib-like elements each extending from the surface of the body, said rib-like elements being narrower in width measured axially of said tubular body than are said first-mentioned elements, and a partition member having a seating surface conforming in curvature to said embossment and seated upon said first-mentioned elements and said rib-like elements.

CHESTER C. MOSS. 

